1. Field of the Invention
The present invention relates to a mobile communication system, and more particularly, to a method for establishing a radio bearer in a mobile communication system.
2. Discussion of the Related Art
3rd Generation Partnership Project (3GPP) wireless communication systems based on Wideband Code Division Multiple Access (WCDMA) radio access technology have been deployed all over the world. High Speed Downlink Packet Access (HSDPA), the first evolution of WCDMA provides the 3GPP with a radio access technology that is highly competitive in a mid-term perspective. Evolved Universal Mobile Telecommunications System (E-UMTS) aims at high competitiveness in a long-term perspective.
FIG. 1 illustrates a network configuration of the E-UMTS. The E-UMTS system is an evolved version of the conventional WCDMA UMTS system and its basic standardization is in progress under the 3GPP. E-UMTS is also called Long Term Evolution (LTE). For details of the technical specifications of UMTS and E-UMTS, refer to Release 7 and Release 8 of “3rd Generation Partnership Project; Technical Specification Group Radio Access Network”.
Referring to FIG. 1, the E-UMTS mainly includes a User Equipment (UE), a base station (or eNB or eNode B), and an Access Gateway (AG) which is located at an end of network (E-UTRAN) and which is connected to an external network. Generally, an eNB can simultaneously transmit multiple data steams for a broadcast service, a multicast service and/or a unicast service. The AG can be divided into a part that handles processing of user traffic and a part that handles processing of control traffic. Here, the AG part for processing new user traffic and the AG part for processing control traffic can communicate with each other using a new interface. One or more cells may exist for one eNB. An interface for transmitting user traffic or control traffic can be used between eNBs. A Core Network (CN) may include the AG and a network node or the like for user registration of the UE. An interface for discriminating between the E-UTRAN and the CN can be used. The AG manages mobility of the UE on a Tracking Area (TA) basis. One TA includes a plurality of cells. When the UE has moved from a specific TA to another TA, the UE notifies the AG that the TA where the UE is located has been changed.
FIG. 2 illustrates a network configuration of an Evolved Universal Terrestrial Radio Access Network (E-UTRAN) system. The E-UTRAN system is an evolved version of the conventional UTRAN system. The E-UTRAN includes a base station that will also be referred to as “eNode B” or “eNB”. eNBs are connected through an X2 interface. Each eNB is connected to the UE through a radio interface and is connected to an Evolved Packet Core (EPC) through an Sl interface.
To conduct communications in a mobile communication system, a UE and an eNB should configure data block formats for data transmission and reception. Conventionally, data block formats are configured without taking into account characteristics of downlink and uplink traffics, thus resulting in dissipation of radio resources.